Collet and pusher



an- 5, 1932- c. A. WEED 1,839,432

COLLET AND PUSHER Filed April 7, 1930 Patented Jan. 5, 11932 rarest errrce CHESTER A. WEED, OF BROOKLYN, NEW YORK, ASSIGNOR TO TEE NATIONAL ACME COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO COLLET AND PUSHER Application filed April 7,

, are so formed that they will have the neces sary flexibility to enable them effectively to grasp the stock or work without affecting the durability thereof, whereby Y the cracking, fracture or breaking off or bending of the fin gers is prevented;

As is well known the pusher is a device used in connection with a feed tube for pushing a stock bar through a work spindle into position to be operated upon. by the tool,

' while a collet is a device frequently used with a pusher for gripping the stock bar after it has been pushed forward by the pusher and both are commonly made with spring fingers and various attempts have been made for 5' 2 some time past to make a practicable and durable collet or pusher but with indifferent success. The dificulty with the spring fingers of these devices has always been that they crack and fracture or break off or bend where they join the body so that the life of the device is comparatively short requiring frequent replacements. I

The usual and common way of making these devices is either to bore out a solid bar into .35 round tubular form and then slit it to form the fingers or to take a tubular bar and slot it to form the spring fingers but the difficulty has been to give the fingers just sufiicient flexi- 1930. Serial No. 442,298.

strain all comes at the corners of each finger,so that there are thus two forces working against each other, a compression and an v expansion, trying to tear the finger apart from its base or body. In other words, in this are or curved form of finger the strain is act ing to compress the finger at the height of the curve or midway between the side edges of the finger, while tending to expand or stretch'it beyond its elastic limit at the outer corners of the finger adjacent to the slots,

and these two forces working in opposition quickly cause the fracture or cracking and consequent breaking of the finger at the juncture point thereof with its body. In short, it has been found impossible to make a satisfactory long-lived article of this kind with spring fingers having proper flexibility when the fingers are arc-shaped, no matter how the device is heat-treated, since the fingers, being curved transversely, have comparatively little flexibility or spring and, therefore, quick ly fracture and break.

Various methods of heat treatment have been tried to prevent this, without success, which, together with the cost of making the collet or pusher. has made them highly expensive due to the frequent renewals necessarv.

Therefore, the object of the present improvement is to overcome these difficulties b eliminating the cause for the cracking and fracturing of the fingers and thus provide a collet or pusher in which the fingers have all the flexibility necessary so that the device slots some of which terminate at the outer or front end of the device while the others terminate short of such end thereof, so that the latter are suitably connected by segmentally shaped solid portions like the inner ends of the fingers which prevents too great/flexibility of the fingers and consequently prehollow or tubular member 2 consis vents the breaking off or cracking of the fingers at the inner or ase ends thereof.

A device without the combination of slots herein shown and having only the short slots and not the longer slots would be an impracticable one or one having comparatively short life since such a device would have to depend entirely upon the fiexibi I the inbent fingers with the result that with these short slots all closed at both ends, it follows their base ends or front ends is prevented by the yielding of the split segmental portions at the front of the device. so that the elastic limit of the fingers can be less than heretofore found necessary and yet the device has equally as greater greater flexibility than heretofore with the result that the fingers need-not be so'resilient as heretofore so that a better and firmer hold on the stock bar is the result with less likelihood of slipping.

In the drawings accompanying and forming a part of this specification- Fig. l is a side view of this improved collet or pusher;

Fig. 2 is a longitudinal sectional view thereof; 7 v

Fig. 3 is a. cross-section thereof taken on the line 8-3 of Fig. 1;

is not limited to the details of constr i and arrangement of parts which ll? rtrated in the accompanying drawings, since the invention is capable of other embodi- 111611 1351 13.1111 that t is phraseology which i employ is for the purpose of description and not of limitation.

T iis improved collet or pusher comprises a ,body portion 8 terminating in a shoulder l and a threaded end 5 and a series of resilient fingers 6 spaced lengthwise from each other. These fingers are formed by slotting the tubular member lengthwise different pre-deter mined v distances.

In the present instance the device is shown provided with a pair of long slots 7 opening at the front end of the collet or pusher and intermediate these long slots are shorter slots 8, the front ends of which intermediate slots are oined together by segmental walls 9 substantially similar to the body portion 10. T he result of this construction is that while all of the slots are segmentally joined at the body portion only some of them are so joined at the free end of the pusher. The device may have a different or a greater number of free ended slots 7 but in all cases it will have between these longer slots one or more shorter slots 8, both ends of which terminate in a segmentally shaped wall. One of the advantages of this construction is that by varying the length of the shorter slot-s greater or less resiliency may be given to the fingers according to the character of the work. Thus all of the fingers between the longer slots always terminate in segmentally shaped walls 9 and these walls materially resist too great a flexibility of the fingers at the base thereof and prevent the difficulties hereinbefore referred In the present instance the structure is shown with two spaced segmentally shaped walls 9 at the free end of the col et or pusher each connecting three fingers 6 together, and these walls resist a too great flexibility of the fingers and thus prevent the cracking or breaking of the fingers at their base ends. The number of these segmental walls may be less or greater according to the number of the longer slots provided but in all instances there will be at least two segmentally shaped walls at the outer ends of the fingers so that at least a plurality of the fingers will be joined at their outer ends in the same manner that they are oined at their inner or base ends.

The fingers intermediate these segmentally shaped or joining walls 9 and 10 are longitudinally bent the required amount toward the axis of the collet, as at 11, to form work or stock bar engaging faces on the inner sides thereof for effectively gripping the work.

Practical tests have proven that this improved device is avery superior one and highly satisfactory as it has just the right amount of flexibility to accomplish the purpose but not sufiicient to cause the breakage or fracture of the fingers at the base thereof. These tests under working conditions have disclosed that the segmental joining walls 9 at the front ends of the collet together with the long slots give considerable flexibility to the fingers and yet resist the opposing strains at the base of the fingers for it is obvious that in the form of device shown the strain would have to be suliicient to break off or fracture or bend at least three of the fingers,the joining segmen wall 9 resisting any one finger fracturing or bending independentlyof ansultably heat treated to properly harden and temper the fingers.

The width of the joining Wall 9 may be varied thereby changing the length of the shorter slots, thus either decreasing or in creasing the flexibility of the fingers, which, as before stated, is a very material advantage, while by having less than-all of the slots so joined at their front ends greater flexibility of the fingers is obtained in that the flexibility of the longitudinally bent fingers is also increased without danger of fracturing or bending the same at bases thereof, with the resultant advantage of enabling the device to be inexpensively made in a simple and expeditious manner and without any of the defects of prior devices.

It is to be understood that by describing in detail herein any particular form, structure or arrangement, it is not intended to limit the invention beyond the terms of the several claims or the requirements of the prior art.

Having thus explained the nature of my said invention and described a way of constructing and using the same, although without atempting to set forth all of the forms in which it may be made, or all of the modes of its use, I claim:

1. A collet or pusher comprising a hollow the body of the device and all but a plurality thereof oined at the forward end by segmentally shaped solid walls thereby to increase the flexibility of the fingers, said wall having a width substantially corresponding to the body of the device.

6. A hollow collet or pusher having a see ries of resilient spaced fingers all joined at their base ends and separated at their front ends to form at least two independent front unconnected sets of connected fingers, each of said fingers being bent inwardly toward the axis of the device thereby to yield with the joined together sets of fingers.

Signed at room 1822 Park Row Building,

city, county and State of New York, this 12th day of March, 1930.

C. A. WEED.

member having a plurality of slots opening at the forward end thereof and therebetween a plurality of spaced resilient fingers joined together at the forward end by a solid wall axis.

2. A collet or pusher comprising a hollow member having a plurality of slots opening at the forward end thereof andtherebetween a pluarlity of spaced resilient fingers joined together at the forward end by a solid segmental wall with the fingers converging inwardly from both ends thereof toward the axls.

3. A collet or pusher comprising a hollow member having a plurality of slots of different lengths, forming spaced fingers longitudinally bent inward toward the axis to impart flexibility thereto, all of said slots joined at the body of the device and some only thereof joined at the forward end thereby to increase the flexibility of the fingers.

4. A collet or pusher comprising a hollow member having a plurality of slots of different lengths, forming spaced fingers longitudinally bent inward toward the axis to im-.

part flexibility thereto, all of said slots joined nally bent inward toward the axis to impart flexibility thereto, all of said slots joined at 

